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Implantation of rat prostate cancer cells into the normal rat prostate results in tumor-stimulating adaptations in the tumor-bearing organ. Similar changes are seen in prostate cancer patients and they are related to outcome. One gene previously found to be upregulated in the non-malignant part of a tumor-bearing prostate lobe in rats was the transcription factor CCAAT/enhancer-binding protein-β (C/EBPβ). To explore this further, we examined C/EBPβ expression by quantitative RT-PCR, immunohistochemistry, and western blot in normal rat prostate tissue surrounding slow-growing non-metastatic Dunning G, rapidly growing poorly metastatic (AT-1), and rapidly growing highly metastatic (MatLyLu) rat prostate tumors―and also by immunohistochemistry in a tissue microarray (TMA) from prostate cancer patients managed by watchful waiting.

In rats, C/EBPβ mRNA expression was upregulated in the surrounding tumor-bearing prostate lobe. In tumors and in the surrounding non-malignant prostate tissue, C/EBPβ was detected by immunohistochemistry in some epithelial cells and in infiltrating macrophages. The magnitude of glandular epithelial C/EBPβ expression in the tumor-bearing prostates was associated with tumor size, with distance to the tumor, and with tumor cell metastatic capacity.

In prostate cancer patients, high expression of C/EBPβ in glandular epithelial cells in the surrounding tumor-bearing tissue was associated with accumulation of M1 macrophages (iNOS+) and a favorable outcome. High expression of C/EBPβ in tumor epithelial cells was associated with high Gleason score, high tumor cell proliferation, the presence of metastases at diagnosis, and poor outcome. 

Implantation of rat prostate cancer cells into the normal rat prostate results in tumor-stimulating changes in the tumor-bearing organ, for example growth of the vasculature, an altered extracellular matrix, and influx of inflammatory cells. To investigate this response further, we compared prostate morphology and the gene expression profile of tumor-bearing normal rat prostate tissue (termed tumor-instructed/indicating normal tissue (TINT)) with that of prostate tissue from controls. Dunning rat AT-1 prostate cancer cells were injected into rat prostate and tumors were established after 10 days. As controls we used intact animals, animals injected with heat-killed AT-1 cells or cell culture medium. None of the controls showed morphological TINT-changes. A rat Illumina whole-genome expression array was used to analyze gene expression in AT-1 tumors, TINT, and in medium injected prostate tissue. We identified 423 upregulated genes and 38 downregulated genes (p<0.05, >= 2-fold change) in TINT relative to controls. Quantitative RT-PCR analysis verified key TINT-changes, and they were not detected in controls. Expression of some genes was changed in a manner similar to that in the tumor, whereas other changes were exclusive to TINT. Ontological analysis using GeneGo software showed that the TINT gene expression profile was coupled to processes such as inflammation, immune response, and wounding. Many of the genes whose expression is altered in TINT have well-established roles in tumor biology, and the present findings indicate that they may also function by adapting the surrounding tumor-bearing organ to the needs of the tumor. Even though a minor tumor cell contamination in TINT samples cannot be ruled out, our data suggest that there are tumor-induced changes in gene expression in the normal tumor-bearing organ which can probably not be explained by tumor cell contamination. It is important to validate these changes further, as they could hypothetically serve as novel diagnostic and prognostic markers of prostate cancer.

Background: Implantation of rat prostate cancer cells into the normal rat prostate results in tumor-stimulating adaptations in the tumor-bearing organ. Similar changes are seen in prostate cancer patients and they are related to outcome. One gene previously found to be upregulated in the non-malignant part of tumor-bearing prostate lobe in rats was the transcription factor CCAAT/enhancer-binding protein- (C/EBP).

Methods: To explore this further, we examined C/EBP expression by quantitative RT-PCR, immunohistochemistry, and Western blot in normal rat prostate tissue surrounding slow-growing non-metastatic Dunning G, rapidly growing poorly metastatic (AT-1), and rapidly growing highly metastatic (MatLyLu) rat prostate tumors?and also by immunohistochemistry in a tissue microarray (TMA) from prostate cancer patients managed by watchful waiting.

Results: In rats, C/EBP mRNA expression was upregulated in the surrounding tumor-bearing prostate lobe. In tumors and in the surrounding non-malignant prostate tissue, C/EBP was detected by immunohistochemistry in some epithelial cells and in infiltrating macrophages. The magnitude of glandular epithelial C/EBP expression in the tumor-bearing prostates was associated with tumor size, distance to the tumor, and metastatic capacity. In prostate cancer patients, high expression of C/EBP in glandular epithelial cells in the surrounding tumor-bearing tissue was associated with accumulation of M1 macrophages (iNOS+) and favorable outcome. High expression of C/EBP in tumor epithelial cells was associated with high Gleason score, high tumor cell proliferation, metastases, and poor outcome.

Conclusions: This study suggest that the expression of C/EBP-beta, a transcription factor mediating multiple biological effects, is differentially expressed both in the benign parts of the tumor-bearing prostate and in prostate tumors, and that alterations in this may be related to patient outcome.

In order to grow, tumors need to induce supportive alterations in the tumor-bearing organ, by us named tumor instructed normal tissue (TINT) changes. We now examined if the nature and magnitude of these responses were related to tumor size and aggressiveness. Three different Dunning rat prostate tumor cells were implanted into the prostate of immune-competent rats; 1) fast growing and metastatic MatLyLu tumor cells 2) fast growing and poorly metastatic AT-1 tumor cells, and 3) slow growing and non-metastatic G tumor cells. All tumor types induced increases in macrophage, mast cell and vascular densities and in vascular cell-proliferation in the tumor-bearing prostate lobe compared to controls. These increases occurred in parallel with tumor growth. The most pronounced and rapid responses were seen in the prostate tissue surrounding MatLyLu tumors. They were, also when small, particularly effective in attracting macrophages and stimulating growth of not only micro-vessels but also small arteries and veins compared to the less aggressive AT-1 and G tumors. The nature and magnitude of tumor-induced changes in the tumor-bearing organ are related to tumor size but also to tumor aggressiveness. These findings, supported by previous observation in patient samples, suggest that one additional way to evaluate prostate tumor aggressiveness could be to monitor its effect on adjacent tissues.

Objective: To study bacterial 16S RNA in archival prostate samples from 352 patients with benign prostate hyperplasia (BPH) and evaluate whether the presence of bacterial DNA was different in those who later developed prostate cancer (n = 171) and in the matched controls that did not progress to cancer (n = 181).

Methods: 16S DNA PCR followed by cloning and sequencing the positive samples.

Results: In 96/352 (27%) of the prostate tissue specimens 16S RNA were detected. Sequence analysis revealed Propionibacterium acnes as the predominant microorganism (23% of 16S RNA positive patients). The second most frequent isolate—Escherichia coli was found in 12 (12%) patients. The other isolates included Pseudomonas sp. (3 patients), Actinomyces sp. (2), Streptococcus mutans (1), Corynebacterium sp. (2),Nocardioides sp. (1), Rhodococcus sp. (1) Veillonella sp. (2). In P. acnes positive samples 62% exhibited severe histological inflammation versus 50% in the bacteria-negative group (p = 0.602). The presence of P. acnes in the prostate was associated with prostate cancer development (OR 2.17, 95% CI 0.77–6.95).

Conclusions: This study has revealed P. acnes as the most common bacteria in the prostate in BPH. Further studies are needed to clarify its role in contributing to the development of prostatic inflammation and prostate cancer.

Background: Tumour necrosis factor receptor associated factor 6 (TRAF6) promotes inflammation in response to various cytokines. Aberrant Wnt3a signals promotes cancer progression through accumulation of β-Catenin. Here we investigated a potential role for TRAF6 in Wnt signaling.

Methods: TRAF6 expression was silenced by siRNA in human prostate cancer (PC3U) and human colorectal SW480 cells and by CRISPR/Cas9 in zebrafish. Several biochemical methods and analyses of mutant phenotype in zebrafish were used to analyse the function of TRAF6 in Wnt signaling.

Findings: Wnt3a-treatment promoted binding of TRAF6 to the Wnt co-receptors LRP5/LRP6 in PC3U and LNCaP cells in vitro. TRAF6 positively regulated mRNA expression of β-Catenin and subsequent activation of Wnt target genes in PC3U cells. Wnt3a-induced invasion of PC3U and SW480 cells were significantly reduced when TRAF6 was silenced by siRNA. Database analysis revealed a correlation between TRAF6 mRNA and Wnt target genes in patients with prostate cancer, and high expression of LRP5, TRAF6 and c-Myc correlated with poor prognosis. By using CRISPR/Cas9 to silence TRAF6 in zebrafish, we confirm TRAF6 as a key molecule in Wnt3a signaling for expression of Wnt target genes.

Interpretation: We identify TRAF6 as an important component in Wnt3a signaling to promote activation of Wnt target genes, a finding important for understanding mechanisms driving prostate cancer progression.

Background: Lead time (LT) is of key importance in early detection of cancer, but cannot be directly measured. We have previously provided LT estimates for prostate cancer (PCa) using archived blood samples from cohorts followed for many years without screening. Objective: To determine the association between LT and PCa grade at diagnosis to provide an insight into whether grade progresses or is stable over time. Design, setting, and participants: The setting was three long-term epidemiologic studies in Sweden including men not subject to prostate-specific antigen (PSA) screening. The cohort included 1041 men with PSA of 3-10 ng/ml at blood draw and subsequently diagnosed with PCa with grade data available. Outcome measurements and statistical analysis: Multivariable logistic regression was used to predict high-grade (Gleason grade group >= 2 or World Health Organization grade 3) versus low-grade PCa at diagnosis in terms of LT, defined as the time between the date of elevated PSA and the date of PCa diagnosis with adjustment for cohort and age. Results and limitations: The probability that PCa would be high grade at diagnosis increased with LT. Among all men combined, the risk of high-grade disease increased with LT (odds ratio 1.13, 95% confidence interval [CI] 1.10-1.16; p < 0.0001), with no evidence of differences in effect by age group or cohort. Higher PSA predicted shorter LT by 0.46 yr (95% CI 0.28-0.64; p < 0.0001) per 1 ng/ml increase in PSA. However, there was no interaction between PSA and grade, suggesting that the longer LT for high-grade tumors is not simply related to age. Limitations include the assumption that men with elevated PSA and subsequently diagnosed with PCa would have had biopsy-detectable PCa at the time of PSA elevation. Conclusions: Our data support grade progression, whereby following a prostate over time would reveal transitions from benign to low-grade and then high-grade PCa. Patient summary: Men with a longer lead time between elevated prostate-specific antigen and subsequent prostate cancer diagnosis were more likely to have high-grade cancers at diagnosis.

Prostate tumors are composed of many cell types, yet the biological significances of the different nonepithelial cells have been largely overlooked. According to recent studies, however, the stroma, which constitutes a substantial part of the tumor volume, plays an important role during the initiation, progression, metastasis and metastatic growth of prostate cancers. To explore this further, Dakhova and co-workers compared gene expression in laser microdissected normal peripheral zone stroma with stroma in peripheral zone cancers (only those with reactive stroma grade 3). A total of 544 genes were upregulated and 606 genes downregulated in tumor stroma. The cancer stroma showed signs of formation of nerves, increased number of stem cells, and responses to DNA damage. Further studies are needed to explore the functional consequences of this, particularly the role of nerves. If these stroma changes can be used as prognostic markers, as targets for therapy, and if similar changes occur in metastases also need to be explored.

Background: Novel therapies for men with castration-resistant prostate cancer (CRPC) are needed, particularly for cancers not driven by androgen receptor (AR) activation. Objectives: To identify molecular subgroups of PC bone metastases of relevance for therapy.

Design, setting, and participants: Fresh-frozen bone metastasis samples from men with CRPC (n = 40), treatment-naïve PC (n = 8), or other malignancies (n = 12) were characterized using whole-genome expression profiling, multivariate principal component analysis (PCA), and functional enrichment analysis. Expression profiles were verified by reverse transcription–polymerase chain reaction (RT-PCR) in an extended set of bone metastases (n = 77) and compared to levels in malignant and adjacent benign prostate tissue from patients with localized disease (n = 12). Selected proteins were evaluated using immunohistochemistry. A cohort of PC patients (n = 284) diagnosed at transurethral resection with long follow-up was used for prognostic evaluation.

Results and limitations: The majority of CRPC bone metastases (80%) was defined as AR-driven based on PCA analysis and high expression of the AR, AR co-regulators (FOXA1, HOXB13), and AR-regulated genes (KLK2, KLK3, NKX3.1, STEAP2, TMPRSS2); 20% were non–AR-driven. Functional enrichment analysis indicated high metabolic activity and low immune responses in AR-driven metastases. Accordingly, infiltration of CD3+ and CD68+ cells was lower in AR-driven than in non–AR-driven metastases, and tumor cell HLA class I ABC immunoreactivity was inversely correlated with nuclear AR immunoreactivity. RT-PCR analysis showed low MHC class I expression (HLA-A, TAP1, and PSMB9 mRNA) in PC bone metastases compared to benign and malignant prostate tissue and bone metastases of other origins. In primary PC, low HLA class I ABC immunoreactivity was associated with high Gleason score, bone metastasis, and short cancer-specific survival. Limitations include the limited number of patients studied and the single metastasis sample studied per patient.

Conclusions: Most CRPC bone metastases show high AR and metabolic activities and low immune responses. A subgroup instead shows low AR and metabolic activities, but high immune responses. Targeted therapy for these groups should be explored. Patient summary: We studied heterogeneities at a molecular level in bone metastasis samples obtained from men with castration-resistant prostate cancer. We found differences of possible importance for therapy selection in individual patients.

Background: Patients with metastatic prostate cancer (PC) are treated with androgen deprivation therapy (ADT) that initially reduces metastasis growth, but after some time lethal castration-resistant PC (CRPC) develops. A better understanding of the tumor biology in bone metastases is needed to guide further treatment developments. Subgroups of PC bone metastases based on transcriptome profiling have been previously identified by our research team, and specifically, heterogeneities related to androgen receptor (AR) activity have been described. Epigenetic alterations during PC progression remain elusive and this study aims to explore promoter gene methylation signatures in relation to gene expression and tumor AR activity.

Materials and methods: Genome-wide promoter-associated CpG methylation signatures of a total of 94 tumor samples, including paired non-malignant and malignant primary tumor areas originating from radical prostatectomy samples (n = 12), and bone metastasis samples of separate patients with hormone-naive (n = 14), short-term castrated (n = 4) or CRPC (n = 52) disease were analyzed using the Infinium Methylation EPIC arrays, along with gene expression analysis by Illumina Bead Chip arrays (n = 90). AR activity was defined from expression levels of genes associated with canonical AR activity.

Results: Integrated epigenome and transcriptome analysis identified pronounced hypermethylation in malignant compared to non-malignant areas of localized prostate tumors. Metastases showed an overall hypomethylation in relation to primary PC, including CpGs in the AR promoter accompanied with induction of AR mRNA levels. We identified a Methylation Classifier for Androgen receptor activity (MCA) signature, which separated metastases into two clusters (MCA positive/negative) related to tumor characteristics and patient prognosis. The MCA positive metastases showed low methylation levels of genes associated with canonical AR signaling and patients had a more favorable prognosis after ADT. In contrast, MCA negative patients had low AR activity associated with hypermethylation of AR-associated genes, and a worse prognosis after ADT.

Conclusions: A promoter methylation signature classifies PC bone metastases into two groups and predicts tumor AR activity and patient prognosis after ADT. The explanation for the methylation diversities observed during PC progression and their biological and clinical relevance need further exploration.

Background: Taxane treatment may be a suitable therapeutic option for patients with castration‐resistant prostate cancer and high expression of constitutively active androgen receptor variants (AR‐Vs). The aim of the study was to compare the effects of cabazitaxel and androgen deprivation treatments in a prostate tumor xenograft model expressing high levels of constitutively active AR‐V7. Furthermore, mechanisms behind acquired cabazitaxel resistance were explored.

Methods: Mice were subcutaneously inoculated with 22Rv1 cells and treated with surgical castration (n = 7), abiraterone (n = 9), cabazitaxel (n = 6), castration plus abiraterone (n = 8), castration plus cabazitaxel (n = 11), or vehicle and/or sham operation (n = 23). Tumor growth was followed for about 2 months or to a volume of approximately 1000 mm3. Two cabazitaxel resistant cell lines; 22Rv1‐CabR1 and 22Rv1‐CabR2, were established from xenografts relapsing during cabazitaxel treatment. Differential gene expression between the cabazitaxel resistant and control 22Rv1 cells was examined by whole‐genome expression array analysis followed by immunoblotting, immunohistochemistry, and functional pathway analysis.

Results: Abiraterone treatment alone or in combination with surgical castration had no major effect on 22Rv1 tumor growth, while cabazitaxel significantly delayed and in some cases totally abolished 22Rv1 tumor growth on its own and in combination with surgical castration. The cabazitaxel resistant cell lines; 22Rv1‐CabR1 and 22Rv1‐CabR2, both showed upregulation of the ATP‐binding cassette sub‐family B member 1 (ABCB1) efflux pump. Treatment with ABCB1 inhibitor elacridar completely restored susceptibility to cabazitaxel, while treatment with AR‐antagonists bicalutamide and enzalutamide partly restored susceptibility to cabazitaxel in both cell lines. The cholesterol biosynthesis pathway was induced in the 22Rv1‐CabR2 cell line, which was confirmed by reduced sensitivity to simvastatin treatment.

Conclusions: Cabazitaxel efficiently inhibits prostate cancer growth despite the high expression of constitutively active AR‐V7. Acquired cabazitaxel resistance involving overexpression of efflux transporter ABCB1 can be reverted by bicalutamide or enzalutamide treatment, indicating the great clinical potential for combined treatment with cabazitaxel and anti‐androgens.

The tumor stroma is vital to tumor development, progression, and metastasis. Cancer-associated fibroblasts (CAF) are among the abundant cell types in the tumor stroma, but the range of their contributions to cancer pathogenicity has yet to be fully understood. Here, we report a critical role for upregulation of the TGF beta/BMP family member GDF15 (MIC-1) in tumor stroma. GDF15 was found upregulated in situ and in primary cultures of CAF from prostate cancer. Ectopic expression of GDF15 in fibroblasts produced prominent paracrine effects on prostate cancer cell migration, invasion, and tumor growth. Notably, GDF15-expressing fibroblasts exerted systemic in vivo effects on the outgrowth of distant and otherwise indolent prostate cancer cells. Our findings identify tumor stromal cells as a novel source of GDF15 in human prostate cancer and illustrate a systemic mechanism of cancer progression driven by the tumor microenvironment. Further, they provide a functional basis to understand GDF15 as a biomarker of poor prognosis and a candidate therapeutic target in prostate cancer. (C)2014 AACR.

Clinical intervention studies and experimental studies with lignan-rich diets suggest that lignans may have inhibitory effects on prostate cancer, but no clinical or experimental studies with purified lignans have been published. The purpose of this study was to investigate the effect of a plant lignan 7-hydroxymatairesinol (HMR) on LNCaP human prostate cancer xenografts in athymic mice. Athymic nude male mice were injected subcutaneously with LNCaP cells. Starting 3 days after tumor cell injections, a control diet or a control diet supplemented with 0.15% or 0.30% of HMR was administered to mice and the tumor take rate and growth was observed for 9 weeks. HMR diet inhibited the growth of LNCaP tumors. Mice treated with HMR had smaller tumor volume, lower tumor take rate, increased proportion of nongrowing tumors, and higher tumor cell apoptotic index compared with controls. Furthermore, the cell proliferation index was reduced in mice receiving the 0.30% HMR diet compared with mice receiving the control diet. Our results suggest that dietary HMR started at the early phase of the tumor development inhibits the growth of the LNCaP human prostate cancer xenografts in athymic male mice.

The tactile resonance method (TRM) and Raman spectroscopy (RS) are promising for tissue characterization in vivo. Our goal is to combine these techniques into one instrument, to use TRM for swift scanning, and RS for increasing the diagnostic power. The aim of this study was to determine the classification accuracy, using support vector machines, for measurements on porcine tissue and also produce preliminary data on human prostate tissue. This was done by developing a new experimental set-up combining micro-scale TRMscanning haptic microscopy (SHM)for assessing stiffness on a micro-scale, with fibre optic RS measurements for assessing biochemical content. We compared the accuracy using SHM alone versus SHM combined with RS, for different degrees of tissue homogeneity. The cross-validation classification accuracy for healthy porcine tissue types using SHM alone was 6581%, and when RS was added it increased to 8187%. The accuracy for healthy and cancerous human tissue was 6770% when only SHM was used, and increased to 7277% for the combined measurements. This shows that the potential for swift and accurate classification of healthy and cancerous prostate tissue is high. This is promising for developing a tool for probing the surgical margins during prostate cancer surgery. 

In the light of findings indicating that cannabinoids can affect the proliferation of a number of cancer cell types and that cannabinoid receptor expression is higher in prostate cancer cell lines than in non-malignant cells, we investigated whether the level of cannabinoid 1 receptor immunoreactivity (CB(1)IR) in prostate cancer tissues is associated with disease severity and outcome. Formalin-fixed paraffin-embedded non-malignant and tumour tissue samples from patients who were diagnosed with prostate cancer at a transurethral resection for voiding problems were used. CB(1)IR, which was scored in a total of 399 cases, was associated with the epithelial cell membranes, with little staining in the stroma. Patients with a tumour CB(1)IR score greater or equal to the median (2) had a significantly higher proportion of Gleason scores 8-10, metastases at diagnosis, tumour size and rate of cell proliferation at diagnosis than patients with a score<2. For 269 cases, tumour CB(1)IR was measured for patients who only received palliative therapy at the end stages of the disease, allowing the influence of CB(1)IR upon the disease outcome to be determined. Receiver operating characteristic (ROC) curves showed an area under the curve of 0.67 (95% confidence limits 0.59-0.74) for CB(1)IR in the tumour. CB(1)IR in non-malignant tissue was not associated with disease outcome. A tumour CB(1)IR score >or=2 was associated with a significantly lower disease specific survival. A Cox proportional hazards regression indicated that the tumour CB(1)IR score and the Gleason score were independent prognostic variables. It is concluded that a high tumour CB(1)IR score is associated with prostate cancer severity and outcome.

Background. Spinal cord compression is an oncological and surgical emergency. Delays in referral and diagnosis may influence functional outcome. It is therefore important to identify patients who will regain or maintain ability to walk after surgery. The aim of the present study was to examine current practice for referral and diagnosis of prostate cancer patients with spinal cord compression and to identify prognostic factors for neurological outcome after surgery.

Patients and methods. The study includes 68 consecutive patients with prostate cancer who underwent surgery due to neurological compromise.  Intervals from onset of neurological symptoms to referral, diagnosis, and treatment were analyzed in relation to functional outcome. The prognostic significance of preoperative clinical parameters on gait function one month after surgery was evaluated.

Results. Patients who were referred from local hospitals had longer delay to surgery than those who directly presented to the cancer centre (p=0.004). The rate of diagnosis with MRI increased through the week and peaked on Friday, with few patients being diagnosed during weekends. Ability to walk before surgery, hormone-naive prostate cancer, and/or shorter time from loss of ambulation were associated with more favorable neurological outcome. In patients with hormone-refractory disease who were unable to walk before surgery regaining of ambulation was associated with: duration of paresis <48 hours (p=0.005), good preoperative performance status (p=0.04), preoperative PSA serum level <200 ng/ml (p=0.03), and surgery with posterior decompression and stabilization (p=0.03).

Conclusion. Early diagnosis and rapid treatment of spinal cord compression in prostate cancer patients is crucial for neurological recovery. Rising of awareness for the condition among patients at risk and among physicians is mandatory as well as improvement of local and regional guidelines for treatment.

Background and purpose The criteria for selecting patients who may benefit from surgery of spinal cord compression in metastatic prostate cancer are poorly defined. We therefore studied patients operated for metastatic spinal cord compression in order to evaluate outcome of surgery and to find predictors of survival. Patients and methods We reviewed the records of 54 consecutive patients with metastatic prostate cancer who were operated for spinal cord compression at Umeå University Hospital. The indication for surgery was neurological deficit due to spinal cord compression. 41 patients had hormone-refractory cancer and 13 patients had previously untreated, hormone-naïve prostate cancer. 29 patients were operated with posterior decompression only, and in 25 patients posterior decompression and stabilization was performed. Results Preoperatively, 6/54 of patients were able to walk. 1 month after surgery, 33 patients were walking, 15 were non-ambulatory, and 6 had died. Mortality rate was 11% at 1 month, 41% at 6 months, and 59% at 1 year. In the hormone-naïve group, 8/13 patients were still alive with a median postoperative follow-up of 26 months. In the hormone-refractory group, median survival was 5 months. Patients with hormone-refractory disease and Karnofsky performance status (KPS) of ≤ 60% had median survival of 2.5 months, whereas those with KPS of 70% and KPS of ≥ 80% had a median survival of 7 months and 18 months, respectively (p < 0.001). Visceral metastases were present in 12/41 patients with hormone-refractory tumor at the time of spinal surgery, and their median survival was 4 months-as compared to 10 months in patients without visceral metastases (p = 0.003). Complications within 30 days of surgery occurred in 19/54 patients. Interpretation Our results indicate that patients with hormone-naive disease, and those with hormone-refractory disease with good performance status and lacking visceral metastases, may be helped by surgery for metastatic spinal cord compression.

Androgen receptors (ARs) are probably of importance during all phases of prostate cancer (PC) growth, but their role in bone metastases is largely unexplored. Bone metastases were therefore collected from hormone-naive (n=11), short-term castrated (n=7) and castration-resistant PC (CRPC, n=44) patients by biopsy (n=4) or at surgery to alleviate symptoms from metastases complications (metastasis surgery, n=58), and immunostained for nuclear ARs, Ki67, active caspase-3, prostate-specific antigen (PSA) and chromogranin A, and results were related to serum PSA, treatments and outcome. Nuclear AR immunostaining was decreased and apoptosis was increased, but cell proliferation remained largely unaffected in metastases within a few days after surgical castration. In CRPC patients, nuclear AR staining of metastases was increased when compared to short-term castrated patients. The nuclear AR staining score was related to tumour cell proliferation, but it was not associated with other downstream effects of AR activation such as apoptosis and PSA staining, and it was only marginally related to the presence of neuroendocrine tumour cells. Serum PSA at metastasis surgery, although related to outcome, was not associated with AR staining, markers of metastasis growth or PSA staining in metastases. High nuclear AR immunostaining was associated with a particularly poor prognosis after metastasis surgery in CRPC patients, suggesting that such men may benefit from the potent AR blockers now tested in clinical trials.

Study design. We retrospectively analyzed prognostic factors for survival in prostate cancer patients operated for metastatic spinal cord compression.

Objective. The aim was to obtain a clinical score for prediction of survival after surgery.

Summary of background data. Survival prognosis is important when deciding about treatment of patients with metastatic spinal cord compression. The criteria for identifying prostate cancer patients who may benefit from surgical treatment are unclear.

Patients and methods The study comprised 68 consecutive patients with prostate cancer operated for metastatic spinal cord compression at Umeå University Hospital, Sweden. The indication for surgery was neurological deficit; 53 patients had hormone-refractory prostate cancer, and 15 patients had previously untreated, hormone-naïve prostate cancer. In 42 patients posterior decompression was performed and 26 patients were operated with posterior decompression and stabilization.

Results A new score for prediction of survival was developed based on the results of survival analyses. The score includes: hormone status of prostate cancer, Karnofsky performance status, evidence of visceral metastasis, and preoperative serum PSA. The total scores ranged from 0 to 6. Three prognostic groups were formulated: group A (n = 32) with scores 0-1; group B (n = 23) with scores 2-4, and group C (n = 12) with scores 5-6. The median overall survival was 3 (0.3 - 20) months in group A, 16 (1.8 - 59) months in group B, and in group C more than half (7 of 12) of patients were still alive.

Conclusion We present a new prognostic score for predicting survival of prostate cancer patients after surgery for metastatic spinal cord compression. The score is easy to apply in clinical practice and may be used as additional support when making decision about treatment.

BACKGROUND: The relation between androgen receptor (AR) gene amplification and other mechanisms behind castration-resistant prostate cancer (CRPC), such as expression of constitutively active AR variants and steroid-converting enzymes has been poorly examined. Specific aim was to examine AR amplification in PC bone metastases and to explore molecular and functional consequences of this, with the long-term goal of identifying novel molecular targets for treatment. METHODS: Gene amplification was assessed by fluorescence in situ hybridization in cryo-sections of clinical PC bone metastases (n = 40) and by PCR-based copy number variation analysis. Whole genome mRNA expression was analyzed using H12 Illumina Beadchip arrays and specific transcript levels were quantified by qRT-PCR. Protein localization was analyzed using immunohistochemistry and confocal microscopy. The YIPF6 mRNA expression was transiently knocked down and stably overexpressed in the 22Rv1 cell line as representative for CRPC, and effects on cell proliferation, colony formation, migration, and invasion were determined in vitro. Extracellular vesicles (EVs) were isolated from cell cultures using size-exclusion chromatography and enumerated by nanoparticle tracking analysis. Protein content was identified by LC-MS/MS analysis. Blood coagulation was measured as activated partial thromboplastin time (APTT). Functional enrichment analysis was performed using the MetaCore software. RESULTS: AR amplification was detected in 16 (53%) of the bone metastases examined from CRPC patients (n = 30), and in none from the untreated patients (n = 10). Metastases with AR amplification showed high AR and AR-V7 mRNA levels, increased nuclear AR immunostaining, and co-amplification of genes such as YIPF6 in the AR proximity at Xq12. The YIPF6 protein was localized to the Golgi apparatus. YIPF6 overexpression in 22Rv1 cells resulted in reduced cell proliferation and colony formation, and in enhanced EV secretion. EVs from YIPF6 overproducing 22Rv1 cells were enriched for proteins involved in blood coagulation and, accordingly, decreased the APTT in a dose-dependent fashion. CONCLUSIONS: AR amplified CRPC bone metastases show high AR-V7 expression that probably gives resistance to AR-targeting drugs. Co-amplification of the Golgi protein coding YIPF6 gene with the AR may enhance the secretion of pro-coagulative EVs from cancer cells and thereby stimulate tumor progression and increase the coagulopathy risk in CRPC patients.

Background: Prostate cancer (PC) is a heterogenous multifocal disease ranging from indolent to lethal states. For improved treatment-stratification, reliable approaches are needed to faithfully differentiate between high- and low-risk tumors and to predict therapy response at diagnosis.

Methods: A metabolomic approach based on high resolution magic angle spinning nuclear magnetic resonance (HR MAS NMR) analysis was applied on intact biopsies samples (n = 111) obtained from patients (n = 31) treated by prostatectomy, and combined with advanced multi- and univariate statistical analysis methods to identify metabolomic profiles reflecting tumor differentiation (Gleason scores and the International Society of Urological Pathology (ISUP) grade) and subtypes based on tumor immunoreactivity for Ki67 (cell proliferation) and prostate specific antigen (PSA, marker for androgen receptor activity).

Results: Validated metabolic profiles were obtained that clearly distinguished cancer tissues from benign prostate tissues. Subsequently, metabolic signatures were identified that further divided cancer tissues into two clinically relevant groups, namely ISUP Grade 2 (n = 29) and ISUP Grade 3 (n = 17) tumors. Furthermore, metabolic profiles associated with different tumor subtypes were identified. Tumors with low Ki67 and high PSA (subtype A, n = 21) displayed metabolite patterns significantly different from tumors with high Ki67 and low PSA (subtype B, n = 28). In total, seven metabolites; choline, peak for combined phosphocholine/glycerophosphocholine metabolites (PC + GPC), glycine, creatine, combined signal of glutamate/glutamine (Glx), taurine and lactate, showed significant alterations between PC subtypes A and B.

Conclusions: The metabolic profiles of intact biopsies obtained by our non-invasive HR MAS NMR approach together with advanced chemometric tools reliably identified PC and specifically differentiated highly aggressive tumors from less aggressive ones. Thus, this approach has proven the potential of exploiting cancer-specific metabolites in clinical settings for obtaining personalized treatment strategies in PC.

Background: Prostate cancer (PC) can display very heterogeneous phenotypes ranging from indolent asymptomatic to aggressive lethal forms. Understanding how these PC subtypes vary in their striving for energy and anabolic molecules is of fundamental importance for developing more effective therapies and diagnostics. Here, we carried out an extensive analysis of prostate tissue samples to reveal metabolic alterations during PC development and disease progression and furthermore between TMPRSS2-ERG rearrangement-positive and -negative PC subclasses.

Methods: Comprehensive metabolomics analysis of prostate tissue samples was performed by non-destructive high-resolution magic angle spinning nuclear magnetic resonance (H-1 HR MAS NMR). Subsequently, samples underwent moderate extraction, leaving tissue morphology intact for histopathological characterization. Metabolites in tissue extracts were identified by H-1/P-31 NMR and liquid chromatography-mass spectrometry (LC-MS). These metabolomics profiles were analyzed by chemometric tools and the outcome was further validated using proteomic data from a separate sample cohort.

Results: The obtained metabolite patterns significantly differed between PC and benign tissue and between samples with high and low Gleason score (GS). Five key metabolites (phosphocholine, glutamate, hypoxanthine, arginine and alpha-glucose) were identified, who were sufficient to differentiate between cancer and benign tissue and between high to low GS. In ERG-positive PC, the analysis revealed several acylcarnitines among the increased metabolites together with decreased levels of proteins involved in beta-oxidation; indicating decreased acyl-CoAs oxidation in ERG-positive tumors. The ERG-positive group also showed increased levels of metabolites and proteins involved in purine catabolism; a potential sign of increased DNA damage and oxidative stress.

Conclusions: Our comprehensive metabolomic analysis strongly indicates that ERG-positive PC and ERG-negative PC should be considered as different subtypes of PC; a fact requiring different, sub-type specific treatment strategies for affected patients.

Objectives: Androgen deprivation therapy (ADT) has long been a cornerstone in treatment of advanced prostate cancer (PCa), and is known to improve the results of radiotherapy (RT) for high-risk disease. The purpose of our study was to use a multiplexed immunohistochemical (mIHC) approach to investigate the infiltration of immune cells in PCa tissue after eight weeks of ADT and/or RT with 10 Gy.

Methods: From a cohort of 48 patients divided into two treatment arms, we obtained biopsies before and after treatment and used a mIHC method with multispectral imaging to analyze the infiltration of immune cells in tumor stroma and tumor epithelium, focusing on areas with high infiltration.

Results: Tumor stroma showed a significantly higher infiltration of immune cells compared to tumor epithelium. The most prominent immune cells were CD20+ B-lymphocytes, followed by CD68+ macrophages, CD8+ cytotoxic T-cells, FOXP3+ regulatory T-cells (Tregs), and T-bet+ Th1-cells. Neoadjuvant ADT followed by RT significantly increased the infiltration of all five immune cells. Numbers of Th1-cells and Tregs significantly increased after single treatment with ADT or RT. In addition, ADT alone increased the number of cytotoxic T-cells and RT increased the number of B-cells.

Conclusions: Neoadjuvant ADT in combination with RT results in a higher inflammatory response compared to RT or ADT alone. The mIHC method may be a useful tool for investigating infiltrating immune cells in PCa biopsies to understand how immunotherapeutic approaches can be combined with current PCa therapies.

Castration experiments in rodents show that the stromal vasculature is critical to the androgen-mediated prostate growth regulation. However, the role of angiogenesis inhibitors, such as thrombospondin-1 (TSP-1), in this process is unclear. TSP-1 is a multifunctional glycoprotein that can function as a potent angiogenesis inhibitor and an in vivo activator of latent transforming growth factor-beta (TGF-beta) in some tissues. On the basis of these observations, we hypothesized that TSP-1 regulated androgen withdrawal-induced prostate regression and that this process was mediated not only through antiangiogenic activity but also through TGF-beta activation. To test this, we evaluated angiogenic activity in human prostate epithelial and stromal cells treated with androgens and hypoxia in vitro. TSP-1 knockout mice were characterized to investigate the in vivo functions of TSP-1. In vitro, we found that androgens and hypoxia differentially regulated TSP-1 and angiogenic activity. Androgens stimulated normal epithelial cell, but inhibited normal stromal cell, angiogenic activity. Conversely, hypoxia stimulated stromal while inhibiting epithelial activity. Thus, in vivo, net angiogenic activity must reflect cellular interactions. And, we found that media conditioned by epithelial cells grown under normoxic conditions stimulated stromal cell angiogenic activity, and if epithelial cells were grown under hypoxic conditions, stromal activity was further increased. TSP-1 levels, however, were unchanged. In vivo, TSP-1 loss in a mouse model led to prostate epithelial hyperplasia by 3 months of age with only a modest stromal effect. Androgens suppressed TSP-1 as expression increased after castration both in normal mouse prostate and in human prostate cancer tissues. In addition, TSP-1 expression corresponded to increased TGF-beta activation in mouse tissues, specifically in the stromal compartment. These data show a critical role for TSP-1 in prostate epithelial and stromal growth regulation through angiogenic inhibition and activation of latent TGF-beta. Therefore, loss of TSP-1 during tumorigenesis would eliminate two barriers to cancer progression.

In recent years, considerable interest has been generated by findings that cannabinoids not only have useful palliative effects, but also can affect the viability and invasivity of a variety of different cancer cells. In the present review, the potential of targeting the cannabinoid system for the treatment of cancer is considered from a practical, rather than a mechanistic viewpoint, addressing questions such as whether human tumour cells express CB receptors; whether the potencies of action of cannabinoids in vitro match the potencies expected on the base of receptor theory; what is known about the in vivo effects of cannabinoids and cancer, and how relevant the experiments undertaken are to the clinical situation; and finally, what approaches can be taken to minimise unwanted effects of cannabinoid treatment. It is concluded that cannabinoids (or agents modulating the endogenous cannabinoid system) are an attractive target for drug development in the cancer area, but that more in vivo studies, particularly those investigating the potential of cannabinoids as an addition to current treatment strategies, are needed.

These data indicate that a high tumour CB(1) receptor expression at diagnosis augments the deleterious effects of a high pEGFR expression upon disease-specific survival.

Fatty acid amide hydrolase (FAAH) is responsible for the hydrolysis of the endogenous cannabinoid (CB) receptor ligand anandamide. Here we have investigated whether the expression levels of FAAH and CB1 receptors influence the prognostic value of markers of angiogenesis in prostate cancer. Data from a cohort of 419 patients who were diagnosed with prostate cancer at transurethral resection for lower urinary tract symptoms, of whom approximately 2/3 had been followed by expectancy, were used. Scores for the angiogenesis markers endoglin and von Willebrand factor (vWf), the endocannabinoid markers fatty acid amide hydrolase (FAAH) and cannabinoid CB1 receptors and the cell proliferation marker Ki-67 were available in the database. For the cases followed by expectancy, the prognostic value of endoglin was dependent upon the tumour epithelial FAAH immunoreactivity (FAAH-IR) and CB1IR scores, and the non-malignant epithelial FAAH-IR scores, but not the non-malignant CB1IR scores or the tumour blood vessel FAAH-IR scores. This dependency upon the tumour epithelial FAAH-IR or CB1IR scores was less apparent for vWf, and was not seen for Ki-67. Using an endoglin cut-off value of 10 positively stained vessels per core and a median split of tumour FAAH-IR, four groups could be generated, with 15 year of disease-specific survival (%) of 68 +/- 7 (low endoglin, low FAAH), 45 +/- 11 (high endoglin, low FAAH), 77 +/- 6 (low endoglin, high FAAH) and 21 +/- 10 (high endoglin, high FAAH). Thus, the cases with high endoglin and high FAAH scores have the poorest rate of disease-specific survival. At diagnosis, the number of cases with tumour stages 1a-1b relative to stages 2-4 was sensitive to the endoglin score in a manner dependent upon the tumour FAAH-IR. It is concluded that the prognostic value of endoglin as a marker of neovascularisation in prostate cancer can be influenced by the expression level of markers of the endocannabinoid system. This article is part of a Special Issue entitled Lipid Metabolism in Cancer.

Background: Progress in cancer biomarker discovery is dependent on access to high-quality biological materials and high-resolution clinical data from the same cases. To overcome current limitations, a systematic prospective longitudinal sampling of multidisciplinary clinical data, blood and tissue from cancer patients was therefore initiated in 2010 by Uppsala and Umea Universities and involving their corresponding University Hospitals, which are referral centers for one third of the Swedish population.

Material and Methods: Patients with cancer of selected types who are treated at one of the participating hospitals are eligible for inclusion. The healthcare-integrated sampling scheme encompasses clinical data, questionnaires, blood, fresh frozen and formalin-fixed paraffin-embedded tissue specimens, diagnostic slides and radiology bioimaging data.

Results: In this ongoing effort, 12,265 patients with brain tumors, breast cancers, colorectal cancers, gynecological cancers, hematological malignancies, lung cancers, neuroendocrine tumors or prostate cancers have been included until the end of 2016. From the 6914 patients included during the first five years, 98% were sampled for blood at diagnosis, 83% had paraffin-embedded and 58% had fresh frozen tissues collected. For Uppsala County, 55% of all cancer patients were included in the cohort.

Conclusions: Close collaboration between participating hospitals and universities enabled prospective, longitudinal biobanking of blood and tissues and collection of multidisciplinary clinical data from cancer patients in the U-CAN cohort. Here, we summarize the first five years of operations, present U-CAN as a highly valuable cohort that will contribute to enhanced cancer research and describe the procedures to access samples and data.

Background and purpose: Dose escalation in external radiotherapy of prostate cancer shows promising results in terms of biochemical disease-free survival. Boost volume delineation guidelines are sparse which may cause high interobserver variability. The aim of this research was to characterize gross tumor volume (GTV) delineations based on multiparametric magnetic resonance imaging (mpMRI) and prostate specific membrane antigen-positron emission tomography (PSMA-PET) in relation to histopathology-validated Gleason grade 4 and 5 regions.

Material and methods: The study participants were examined with [68Ga]PSMA-PET/mpMRI prior to radical prostatectomy. Four radiation oncologists delineated GTVs in 15 study participants, on four different image types; T2-weighted (T2w), diffusion weighted imaging (DWI), dynamic contrast enhanced (DCE) and PSMA-PET scans separately. The simultaneous truth and performance level estimation (STAPLE) algorithm was used to generate combined GTVs. GTVs were subsequently compared to histopathology. We analysed how Dice similarity coefficient (DSC) and lesion coverage are affected by using single versus multiple image types as well as by adding a clinical target volume (CTV) margin.

Results: Median DSC (STAPLE) for different GTVs varied between 0.33 and 0.52. GTVPSMA-PET/mpMRI generated the highest median lesion coverage at 0.66. Combining different image types achieved similar lesion coverage as adding a CTV margin to contours from a single image type, while reducing non-malignant tissue inclusion within the target volume.

Conclusion: The combined use of mpMRI or PSMA-PET/mpMRI shows promise, achieving higher DSC and lesion coverage while minimizing non-malignant tissue inclusion, in comparison to the use of a single image type with an added CTV margin.

Transforming growth factor beta (TGF beta) is a key regulator of epithelial-tomesenchymal transition (EMT) during embryogenesis and in tumors. The effect of TGF beta, on EMT, is conveyed by induction of the pro-invasive transcription factor Snail1. In this study, we report that TGF beta stimulates Snail1 sumoylation in aggressive prostate, breast and lung cancer cells. Sumoylation of Snail1 lysine residue 234 confers its transcriptional activity, inducing the expression of classical EMT genes, as well as TGF beta receptor I (T beta RI) and the transcriptional repressor Hes1. Mutation of Snail1 lysine residue 234 to arginine (K234R) abolished sumoylation of Snail1, as well as its migratory and invasive properties in human prostate cancer cells. An increased immunohistochemical expression of Snail1, Sumo1, T beta RI, Hes1, and c-Jun was observed in aggressive prostate cancer tissues, consistent with their functional roles in tumorigenesis.

Transforming growth factor-beta (TGF beta) can be both a tumor promoter and suppressor, although the mechanisms behind the protumorigenic switch remain to be fully elucidated. The TGF beta type I receptor (T beta RI) is proteolytically cleaved in the ectodomain region. Cleavage requires the combined activities of tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) and TNF-alpha-converting enzyme (TACE). The cleavage event occurs selectively in cancer cells and generates an intracellular domain (ICD) of T beta RI, which enters the nucleus to mediate gene transcription. Presenilin 1 (PS1), a gamma-secretase catalytic core component, mediates intramembrane proteolysis of transmembrane receptors, such as Notch. We showed that TGF beta increased both the abundance and activity of PS1. TRAF6 recruited PS1 to the T beta RI complex and promoted lysine-63-linked polyubiquitination of PS1, which activated PS1. Furthermore, PS1 cleaved T beta RI in the transmembrane domain between valine-129 and isoleucine-130, and ICD generation was inhibited when these residues were mutated to alanine. We also showed that, after entering the nucleus, T beta RI-ICD bound to the promoter and increased the transcription of the gene encoding T beta RI. The TRAF6- and PS1-induced intramembrane proteolysis of T beta RI promoted TGF beta-induced invasion of various cancer cells in vitro. Furthermore, when a mouse xenograft model of prostate cancer was treated with the gamma-secretase inhibitor DBZ {(2S)-2-[2-(3,5-difluorophenyl)-acetylamino]-N-(5-methyl-6-oxo-6,7-dihydro-5H-dibenzo[b, d]azepin-7-yl)-propionamide}, generation of T beta RI-ICD was prevented, transcription of the gene encoding the proinvasive transcription factor Snail1 was reduced, and tumor growth was inhibited. These results suggest that gamma-secretase inhibitors may be useful for treating aggressive prostate cancer.

Importance of the field: Prostate cancer is a common and multifocal disease but the diagnostic methods available are unsatisfactory. Most tumors present are of low malignant potential, whereas others are highly aggressive. At present, imaging cannot be used to guide tissue biopsies safely towards the most aggressive tumor present. To handle this problem multiple needle biopsies are taken. The biopsies often contain only normal prostate tissue, and even if the tumor is sampled it is not known whether a more aggressive cancer is present elsewhere in the organ. If changes in the normal tissue indicate the presence and nature of tumors, this information could be used to improve diagnostics and prognostics of prostate cancer. Areas covered in this review: Current evidence that the tumor-adjacent morphologically normal prostate tissue is not completely normal is reviewed, and that this tissue, named tumor indicating normal tissue (TINT) by the authors, can be used to diagnose prostate cancer. What the reader will gain: The reader will understand that tumors need to affect their surroundings in order to grow and metastasize and that the normal prostate tissue is therefore tinted by the presence and nature of cancer and that this knowledge can be used to develop new diagnostic and prognostic markers. Take home message: TINT changes could probably, when more rigorously defined and validated, be used to diagnose and prognosticate prostate cancer.

Accumulating data indicates that tumor-derived extracellular vesicles (EVs) are responsible for tumor-promoting effects. However, if tumor EVs also prepare the tumor-bearing organ for subsequent tumor growth, and if this effect is different in low and high malignant tumors is not thoroughly explored. Here we used orthotopic rat Dunning R-3327 prostate tumors to compare the role of EVs from fast growing and metastatic MatLyLu (MLL) tumors with EVs from more indolent and non-metastatic Dunning G (G) tumors. Prostate tissue pre-conditioned with MLL-EVs in vivo facilitated G tumor establishment compared to G-EVs. MLL-EVs increased prostate epithelial proliferation and macrophage infiltration into the prostate compared to G-EVs. Both types of EVs increased macrophage endocytosis and the mRNA expression of genes associated with M2 polarization in vitro, with MLL-EVs giving the most pronounced effects. MLL-EVs also altered the mRNA expression of growth factors and cytokines in primary rat prostate fibroblasts compared to G-EVs, suggesting fibroblast activation. Our findings propose that EVs from metastatic tumors have the ability to prime the prostate tissue and enhance tumor growth to a higher extent than EVs from non-metastatic tumors. Identifying these differences could lead to novel therapeutic targets and potential prognostic markers for prostate cancer.

Background: Microseminoprotein-beta (MSMB) is a major secretory product from prostate epithelial cells. MSMB synthesis is decreased in prostate tumors in relation to tumor grade. MSMB levels are also reduced in the circulation and MSMB is therefore used as a serum biomarker for prostate cancer. We hypothesized that cancers induce a reduction in MSMB synthesis also in the benign parts of the prostate, and that the magnitude of this response is related to tumor aggressiveness. Reduced levels of MSMB in the circulation could therefore be a consequence of reduced MSMB expression not only in tumor tissue but also in the benign prostate tissue.

Methods: MSMB expression was analyzed in prostatectomy specimens from 36 patients using immunohistochemistry and qRT-PCR. MSMB expression in the benign prostate tissue was analyzed in relation to Gleason score, tumor stage, and distance to the tumor. Furthermore, Dunning rat prostate tumors with different aggressiveness were implanted into the prostate of Copenhagen rats to study if this affected the MSMB expression in the tumor-adjacent benign rat prostate tissue.

Results: In prostatectomy specimens, MSMB expression was reduced in prostate tumors but also in the tumor-adjacent benign parts of the prostate. The reduction in tumor MSMB was related to tumor grade and stage, and the reduction in the benign parts of the prostate to tumor grade, stage, and distance to the tumor. Implantation of Dunning cancer cells into the rat prostate resulted in reduced MSMB protein levels in the tumor-adjacent benign prostate tissue. Rapidly growing and metastatic MatLyLu tumors had a more pronounced effect than slow-growing non-metastatic G tumors.

Conclusion: Our data suggest that aggressive prostate tumors suppress MSMB synthesis in the benign prostate and that this could explain why serum levels of MSMB are decreased in prostate cancer patients. This study suggests that markers for aggressive cancer can be found among factors altered in parallel in prostate tumors and in the adjacent benign tissue.

Advanced cancers induce systemic responses. However, if such systemic changes occur already when aggressive tumors are small, have not been thoroughly characterized. Here, we examined how localized prostate cancers of different sizes and metastatic potential affected DNA synthesis in the rest of the prostate and in various remote organs. Non-metastatic Dunning R-3327 G (G) tumor cells, metastatic MatLyLu (MLL) tumor cells, or vehicle were injected into the prostate of immunocompetent rats. All animals received daily injections of Bromodeoxyuridine (BrdU), to label cells/daughter cells with active DNA synthesis. Equal sized G- and MLL-tumors, similarly increased BrdU-labeling in the prostate, lymph nodes and liver compared to tumor-free controls. Prior to metastasis, MLL-tumors also increased BrdU-labeling in bone marrow and lungs compared to animals with G-tumors or controls. In animals with MLL-tumors, BrdU-labeling in prostate, lungs, brown adipose tissue and skeletal muscles increased in a tumor-size-dependent way. Furthermore, MLL-tumors induced increased signs of DNA damage (γH2AX staining) and accumulation of CD68 + macrophages in the lungs. In conclusion, small localized prostate cancers increased DNA synthesis in several remote tissues in a tumor type- and size-dependent way. This may suggest the possibility for early diagnosis of aggressive prostate cancer by examining tumor-induced effects in other tissues.

Aggressive tumors induce tumor-supporting changes in the benign parts of the prostate. One factor that has increased expression outside prostate tumors is hemoxygenase-1 (HO-1). To investigate HO-1 expression in more detail, we analyzed samples of tumor tissue and peritumoral normal prostate tissue from rats carrying cancers with different metastatic capacity, and human prostate cancer tissue samples from primary tumors and bone metastases. In rat prostate tumor samples, immunohistochemistry and quantitative RTPCR showed that the main site of HO-1 synthesis was HO-1(+) macrophages that accumulated in the tumor-bearing organ, and at the tumor-invasive front. Small metastatic tumors were considerably more effective in attracting HO-1(+) macrophages than larger non-metastatic ones. In clinical samples, accumulation of HO-1(+) macrophages was seen at the tumor invasive front, almost exclusively in high-grade tumors, and it correlated with the presence of bone metastases. HO-1(+) macrophages, located at the tumor invasive front, were more abundant in bone metastases than in primary tumors. HO-1 expression in bone metastases was variable, and positively correlated with the expression of macrophage markers but negatively correlated with androgen receptor expression, suggesting that elevated HO-1 could be a marker for a subgroup of bone metastases. Together with another recent observation showing that selective knockout of HO-1 in macrophages reduced prostate tumor growth and metastatic capacity in animals, the results of this study suggest that extratumoral HO-1(+) macrophages may have an important role in prostate cancer.

Prostate cancer generally metastasizes to bone, and most patients have tumor cells in their bone marrow already at diagnosis. Tumor cells at the metastatic site may therefore progress in parallel with those in the primary tumor. Androgen deprivation therapy is often the first-line treatment for clinically detectable prostate cancer bone metastases. Although the treatment is effective, most metastases progress to a castration-resistant and lethal state. To examine metastatic progression in the bone microenvironment, we implanted androgen-sensitive, androgen receptor-positive, and relatively slow-growing Dunning G (G) rat prostate tumor cells into the tibial bone marrow of fully immune-competent Copenhagen rats. We show that tumor establishment in the bone marrow was reduced compared with the prostate, and whereas androgen deprivation did not affect tumor establishment or growth in the bone, this was markedly reduced in the prostate. Moreover, we found that, with time, G tumor cells in the bone microenvironment progress to a more aggressive phenotype with increased growth rate, reduced androgen sensitivity, and increased metastatic capacity. Tumor cells in the bone marrow encounter lower androgen levels and a higher degree of hypoxia than at the primary site, which may cause high selective pressures and eventually contribute to the development of a new and highly aggressive tumor cell phenotype. It is therefore important to specifically study progression in bone metastases. This tumor model could be used to increase our understanding of how tumor cells adapt in the bone microenvironment and may subsequently improve therapy strategies for prostate metastases in bone.

Prostate cancer is a multifocal disease, but if and how individual prostate tumours influence each other is largely unknown. We therefore explored signs of direct or indirect tumour–tumour interactions in experimental models and patient samples. Low‐metastatic AT1 and high‐metastatic MatLyLu (MLL) Dunning rat prostate cancer cells were injected into separate lobes of the ventral prostate of immunocompetent rats. AT1 tumours growing in the same prostate as MLL tumours had increased tumour size and proliferation compared to AT1 tumours growing alone. In addition, the vasculature and macrophage density surrounding the AT1 tumours were increased by MLL tumour closeness. In patient prostatectomy samples, selected to contain an index tumour [tumour with the highest grade, International Society of Urological Pathology (ISUP) grade 1, 2, 3 or 4] and a low‐grade satellite tumour (ISUP grade 1), cell proliferation in low‐grade satellite tumours gradually increased with increasing histological grade of the index tumour. The density of blood vessels and CD68⁺ macrophages also increased around the low‐grade satellite tumour if a high‐grade index tumour was present. This suggests that high‐grade tumours, by changing the prostate microenvironment, may increase the aggressiveness of low‐grade lesions in the organ. Future studies are needed to explore the mechanisms behind tumour–tumour interactions and their clinical importance.

Pigment epithelium-derived factor (PEDF) is a potent inhibitor of angiogenesis but whether it has additional effects on the tumor microenvironment is largely unexplored. We show that overexpression of PEDF in orthotopic MatLyLu rat prostate tumors increased tumor macrophage recruitment. The fraction of macrophages expressing inducible nitric oxide synthase, a marker of cytotoxic M1 macrophages, was increased, suggesting that PEDF could enhance antitumor immunity. In addition, PEDF overexpression reduced vascular growth both in the tumor and in the surrounding normal tissue, slowed tumor growth, and decreased lymph node metastasis. Contrary, extratumoral lymphangiogenesis was increased. PEDF expression is, for reasons unknown, often decreased or lost during prostate tumor progression. When AT-1 rat prostate tumor cells, expressing high levels of PEDF messenger RNA (mRNA) and protein, were injected into the prostate, PEDF is markedly downregulated, suggesting that factors in the microenvironment suppressed its expression. One such factor could be macrophage-derived tumor necrosis factor alpha (TNFα). A fraction of the accumulating macrophages expressed TNFα, and TNFα treatment downregulated the expression of PEDF protein and mRNA in prostate AT-1 tumor cells in vitro and in the rat ventral prostate in vivo. PEDF apparently has multiple effects in prostate tumors: it suppresses angiogenesis and metastasis, but it also causes macrophage accumulation. Accumulating macrophages may inhibit tumor growth, but they may also suppress PEDF and enhance lymph angiogenesis and, in this way, eventually enhance tumor growth.

Tumor-associated macrophages are involved in angiogenesis and tumor progression, but their role and specific site of action in prostate cancer remain unknown. To explore this, Dunning R-3327 AT-1 rat prostate tumor cells were injected into the prostate of syngenic and immunocompetent Copenhagen rats and analyzed at different time points for vascular proliferation and macrophage density. Endothelial proliferation increased with tumor size both in the tumor and importantly also in the extratumoral normal prostate tissue. Macrophages accumulated in the tumor and in the extratumoral normal prostate tissue and were most abundant in the invasive zone. Moreover, only extratumoral macrophages showed strong positive associations with tumor size and extratumoral vascular proliferation. Treatment with clodronate-encapsulated liposomes reduced the monocyte/macrophage infiltration and resulted in a significant inhibition of tumor growth. This was accompanied by a suppressed proliferation in microvessels and in the extratumoral prostate tissue also in arterioles and venules. The AT-1 tumors produced, as examined by RT(2) Profiler PCR arrays, numerous factors promoting monocyte recruitment, angiogenesis, and tissue remodeling. Several, namely, chemokine (C-C) ligand 2, fibroblast growth factor 2, matrix metalloproteinase 9, interleukin 1beta, interferon gamma, and transforming growth factor beta, were highly upregulated by the tumor in vivo compared with tumor cells in vitro, suggesting macrophages as a plausible source. In conclusion, we here show the importance of extratumoral monocytes/macrophages for prostate tumor growth, angiogenesis, and extratumoral arteriogenesis. Our findings identify tumor-associated macrophages and several chemotactic and angiogenic factors as potential targets for prostate cancer therapy.

TGF-β signaling stimulates various intracellular pathways that can promote migration in tumor cells. These pathways are generally thought to be either dependent or independent of transcription factors called SMADs. One of the SMAD-independent pathways (PI3K-AKT) is mediated by a direct interaction between PI3K and the TGF-β type I receptor. However, Hamidi et al. found that the TGF-β–induced activation of PI3K depends on another ubiquitin ligase–mediated mechanism and a SMAD protein but is independent of the kinase function of TβRI. The binding of TGF-β to its receptor triggered the recruitment of PI3K and the ubiquitin ligase TRAF6, which polyubiquitylated the regulatory PI3K subunit p85α, thus enabling phosphorylation of the catalytic PI3K subunit p110, but only in the presence of SMAD7. The abundance of ubiquitylated p85α correlated with migration in cultured cells and prostate tumor grade in patient samples. TRAF6 mediates activation of the other “SMAD-independent” (JNK) pathway. These data suggest that, although distinct, the TGF-β signaling pathways are not as insulated from each other as was once thought.